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POPULAR SCIENCE REVIEW. 
rocks of Canada^ the Eozoon , the origin of which has caused some difference 
of opinion, and produced a crop of descriptive and controversial, hut for the 
most part technical literature, as to whether the structure was organic and 
foramini feral, or the result of chemical and mineral metamorphism. The 
object of the book is therefore to give a popular account of what is known 
as to the organic structure of the Dawn-animal, stating the substance of all 
that has been previously published, and including many new facts illustra- 
tive of points hitherto more or less obscure. The matter is arranged under 
the following heads : a notice of the Laurentian formation itself ; the 
history of the discovery and proper interpretation of the fossil ; the descrip- 
tion of the Eozoon and its mode of preservation, its contemporaries and 
immediate successors, or those allied to it by zoological affinity, and also the 
objections which have been urged against its organic nature. The lower 
and upper Laurentian rocks are 30,000 feet in thickness, and the Eozoon 
occurs in the lower ; the upper series and the overlying Huronian being 
unfossiliferous, and together with the lower were termed the Azoic, from 
the supposed absence of all living things. Hence the interest in the 
discovery of the presumed dawn of life in the oldest of all the formations 
known to the geologist, and more thoroughly altered cr metamorphosed by 
heat and heated moisture than any others. Under the head. What is 
Eozoon ? Dr. Dawson enters into a full description of the structural 
characters of this form and their relation to other Foraminifera, and gives 
the corroborative opinions of other authors. “Its relation to modern 
animals of its type has been very clearly defined by Dr. Carpenter. In 
the structure of its proper wall and its fine parallel perforations it resembles 
the Nummulites and their allies ; and the animal may be regarded as an 
aberrant member of the Nummuline group, which affords some of the 
largest and most widely distributed of the fossil Foraminifera.’ ’ 
The objections to the animal nature of Eozoon are fairly discussed, and 
of the three general modes for accounting for its existence, first that of 
Professors King and Rowney, who regard the chambers and canals filled 
with serpentine as arising from the erosion or partial dissolving away of the 
serpentine and its replacement by calcite ; and secondly, that Eozoon forms 
are merely peculiar concretions ; both of these are considered not conclusive. 
The third theory, that of filling of cavities by infiltration with serpentine, 
accords with the fact that such infiltration by minerals akin to serpentine 
occurs in fossils in later rocks, and thus explains to some extent the condi- 
tion of Eozoon. 
We may commend the book, with the excellent illustrations and descrip- 
tions, to the careful perusal of those who are interested in the character 
and real nature of the first presumed traces of organic life in the history 
of the earth, so as to understand the strong grounds upon which Dr. Dawson 
and the able naturalists who support his view regard the Eozoon as the 
oldest known Protozoon and related to the Kummulinidse. On the other 
hand, the opponents of the organic character of the Eozoon have, from their 
point of view, given reasons for inferring that the nummuline-like structure 
may be the result of the aggregation and rearrangement of mineral matter 
due to chemical and metamorphic action ; for it must not be forgotten, as 
the author states, that the appreciation of the evidence for such a fossil as 
